Arsenic in Rice

By Bruce Schultz, LSU AgCenter

Dustin Harrell, LSU AgCenter agronomist at the Rice Research Station near Crowley, is participating in a multi-state study on arsenic in rice to determine if levels of the element are higher in different varieties and to see if varied flooding methods affect arsenic content. “Can we change the water management practices to alter the uptake and accumulation of arsenic in rice? That’s what we are investigating,” Harrell says.

All plants naturally absorb arsenic from the soil, but rice tends to absorb more because it is growing in a flooded, anaerobic condition. This makes arsenic more available for uptake by the plant.

Experimental plots at the Rice Research Station are used to test different fertilizer rates and the use of different farming practices. LSU AgCenter agronomist Dustin Harrell said his projects are highly dependent on checkoff funding provided by rice farmers.

Experimental plots at the Rice Research Station are used to test different
fertilizer rates and the use of different farming practices. LSU
AgCenter agronomist Dustin Harrell said his projects are highly
dependent on checkoff funding provided by rice farmers.

Flooding Practices

Different flooding regimes being used include the following:

  • Traditional drill-seeded, delayed-flood management practice where a flood is applied after the rice reaches the three- to four-leaf stage of development and is left until two weeks before harvest.
  • Intermittent flooding, where the initial flood is held for two to three weeks and then allowed to evaporate until mud is exposed, followed by pumping water to a two- to four-inch depth.
  • Semi-aerobic rice management, where flushing is conducted regularly, but aerobic conditions are allowed to persist.
  • Straight head management, where the rice is flooded for 10 days to two weeks followed by draining until the soil cracks and then followed by re-flooding until drained for harvest.

Testing is being conducted in all rice-growing states, including Texas, California, Mississippi, Arkansas, Missouri and Louisiana. Harrell said the flooding practices that allow the field to drain typically will require more weed management – which increases herbicide expenses – increase disease pressure and reduce grain yield.

Varieties And Arsenic Levels

Varieties being tested are CL151, Cheniere, Presidio and Jupiter –along with hybrids CLXL729 and CLXL745. All rice samples will be milled at the Rice Research Station and then sent to a lab for determining inorganic and organic arsenic content, Harrell said. The U.S. Food and Drug Administration has recently reported the results of testing and concluded that no health issues are associated with arsenic in rice and rice products. “This study is simply long-term research to allow Louisiana rice producers to produce the safest, most nutritious rice available for our customers,” says Steve Linscombe, director of the AgCenter Rice Research Station.

Contact Schultz at (337) 788-8821 or bschultz@agcenter.lsu.edu.